There are several testpoints on the underside of the PCB. It is not yet certain what these are for. There is no visible JTAG header.

Photos

Device, front

Device, top

Device, bottom

PCB, top

PCB, bottom

Firmware

You can use the sigrok-fwextract-saleae-logic16 (sic!) tool to extract (from the "Logic" Linux binary; tested with the Saleae 1.2.10 software) the FX3 firmware and the FPGA bitstreams required for using the Saleae Logic Pro 16:

Copy these files to the directory where your libsigrok installation expects them (usually /usr/local/share/sigrok-firmware) and they will be found and used automatically by the libsigrok saleae-logic-pro driver.